Fastening device for a printed circuit board

ABSTRACT

A fastening device attaches a printed circuit board, such as a backplane, within a support framework of an electrical cabinet. The fastening device includes two adjacent members of the support framework. A threaded stud is attached to one of the members and extends toward the adjacent member. A captive fastener is attached to the other adjacent member. The captive fastener has a thread that cooperates with the thread of the stud. The fastener is aligned with the stud, the cooperative thread of the fastener is capable of engaging the thread of the stud. The fastening device secures the printed circuit board between the adjacent members of the support framework.

BACKGROUND OF THE INVENTION

The invention relates generally to electrical cabinets adapted to store, or house, electrical components, and, more particularly to printed circuit boards used in data storage and transfer systems.

As is known in the art, electrical cabinets are used to store, or house, a variety electrical components such as printed circuit boards. The electrical cabinets allow the components within the cabinet to be interconnected and also allow the internal components to be connected to components external to the cabinets. The cabinets typically have an access door and a number of compartments, such as a card cage, i.e., a housing to store the various interconnected printed circuit boards. In addition, the individual components within the cabinet may be replaced or removed to a different location for repair.

Typically, some of the components are printed circuit boards arranged in a card cage, or housing, in an array of vertical or horizontal guide slots (i.e., a linear array of guide slots) provided between opposing sides of the cabinet. Each board is insertable into a corresponding pair of the opposing guide slots and is urged towards the rear of the cabinet to enable an electrical connector mounted to the rear edge of the board to engage, and thereby electrically connect to, a backplane. A backplane typically is a printed circuit board which contains a plurality of electrical connectors. The backplane commonly is referred to as a mother board. The other printed circuit boards discussed above, which connect to the mother board, commonly are referred to as daughter boards.

When electrical cabinets are assembled, backplanes may be installed within housings using loose hardware such as pan-headed screws or flat-headed screws. However, such installation techniques are labor intensive. Also, the loose hardware increases the part counts required to assemble an electrical cabinet, which increases processing time prior to assembly of the electrical cabinet.

Also, existing card cages may secure printed circuit boards, especially backplanes, using hardware that concentrates a load in a small area. For example, a bolt and washer used to secure a printed circuit board has a concentrated load bearing surface and can cause the printed circuit board to, e.g., delaminate.

In addition, card cages of electrical cabinets may not be able to accommodate backplanes having different thicknesses. Typically, generic electrical cabinets are used in systems that are custom tailored. Thus, the structure of a single cabinet may be employed in a system in which different combinations of components and different types of components may be used. These various components may have varying dimensions. Also, several vendors may supply similar components for a system. For example, two different vendors may supply the backplanes for a single system. These different backplanes may have slightly different tolerances due to the differences in manufacturing standards of different vendors.

SUMMARY OF THE INVENTION

One aspect of the invention is a fastening device that attaches a printed circuit board, such as a backplane, within a support framework of an electrical cabinet. The fastening device includes two adjacent members of the support framework. A threaded stud is attached to one of the members and extends toward the adjacent member. A captive fastener is attached to the other adjacent member. The captive fastener has a thread that cooperates with the thread of the stud. The fastener is aligned with the stud, the cooperative thread of the fastener is capable of engaging the thread of the stud. The fastening device secures the printed circuit board between the adjacent members of the support framework.

Preferred embodiments of this aspect of the invention include the following.

The adjacent members are movable relative to one another along a plane in which the members are aligned. The fastener and the stud are aligned along an axis. The fastener includes a hollow cylindrical sleeve that attaches to one of the adjacent members. A shank extends through the sleeve. The shank having a cooperative thread and an internal captivating surface. A head attaches to the shank external to the sleeve with a width greater than an interior width of the sleeve to limit motion of the shank along the axis.

Embodiments within the scope of the claims may have one or more of the following advantages.

The fastening device provides an efficient mechanism to secure a printed circuit board within a housing of an electrical cabinet. The fastening device eliminates the need for loose hardware to secure a printed circuit board within a housing of an electrical cabinet. The fastening mechanism accommodates printed circuit boards having varying thicknesses. The fastening mechanism provides a large load bearing surface to secure a printed circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of an electrical cabinet for storing or housing electrical components such as printed circuit board card cages and printed circuit boards;

FIG. 2 is an isometric view an interior of the electrical cabinet of claim 1;

FIG. 3 is another isometric view of an interior of the electrical cabinet of claim 1;

FIG. 4 is an isometric view of a printed circuit board card cage of the electrical cabinet of FIG. 1, wherein a printed circuit daughter board is shown partially installed;

FIG. 5 is an isometric view of the card cage of FIG. 4, wherein a backplane is shown partially installed;

FIG. 6 is a top schematic view of the card cage of FIG. 4, wherein a ceiling of the card cage is shown in a closed position;

FIG. 7 is an isometric view of a fastener of the card cage of FIG. 4;

FIG. 8 is a side schematic view of the fastener of FIG. 7, wherein portions of the fastener are shown in phantom;

FIG. 9 is an isometric view of a stud of the card cage of FIG. 4;

FIG. 10 is a side schematic view of the stud of FIG. 9;

FIG. 11 is an isometric view of the backplane of FIG. 5;

FIG. 12 is an isometric view of an opposite side of the backplane of FIG. 11;

FIG. 13 is schematic view of a support device of the backplane of FIG. 11;

FIG. 14 is a schematic view of an alternate embodiment of the support device of FIG. 13;

FIG. 15 is an isometric view of the printed circuit daughter board of FIG. 4, wherein two stiffeners are shown attached t Atop and bottom edges of the printed circuit daughter board; and

FIG. 16 is an exploded isometric view of the printed circuit daughter board of FIG. 15.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1-3, an electrical cabinet 100 is adapted for the storage and operation of electrical components, particularly, data storage and transfer technology. For example, electrical components include CPUs, printed circuit boards, batteries, cables, data servers, and laptop computers. Typically, the electrical components are housed within the interior of the cabinet (FIGS. 2 and 3). The electrical components can be interconnected with other components in other electrical cabinets, or are interconnected with other networks. The electrical components reside within various storage compartments 102, 104, 106 within cabinet 100. Electrical cabinet 100 has internal partitions 108 that define the storage compartments 102, 104, 106.

The electrical cabinet 100, has four side-walls 110, 112, 114, 116. Two of the side-walls 110, 114 form access doors. Electrical cabinet 100 stands upright on four wheels 118 and is mobile. Among other elements, electrical cabinet 100 has an extendable platform 120, air vents 122, exhaust fans 124, and a printed circuit board card cage 200.

Referring to FIGS. 4 and 5, printed circuit board card cage 200 provides a housing to support a set of printed circuit boards. Card cage 200 includes two opposing sidewalls 202, 204, a ceiling 206, a movable ceiling member 208, a floor 210, and a movable floor member 212. Sidewalls 202, 204 extend from opposing sides of floor 210 to opposing sides of ceiling 206. Thus, card cage 200 includes an internal space for storing printed circuit boards and defines an opening 214 for receiving a printed circuit board, e.g., a daughter board 216. Card cage 200 is, e.g., 25.8″ in length, 19.9″ in height, and 17.7″ in width.

As shown, both ceiling 206 and floor 210 are permanently and securely fixed to sidewalls 202, 204 by corresponding sets of screws 232 (four screws being shown along each of floor 210 and ceiling 206). Sidewalls 202, 204 are made of a sheet metal, and the edges of sidewalls 202, 204 are molded to form a corrugated-like section that provides additional structural support framework 220. Thus, floor 210, ceiling 206, and sidewalls 202, 204 provide a predefined structure that resists deformation and is able to properly align printed circuit boards within card cage 200.

As shown, sidewalls 202, 204 are substantially solid having only several holes punched to accommodate screws and provide certain other surfaces discussed below. Alternatively, sidewalls 202, 204 could be substantially open, e.g., providing only a structural support framework to accommodate daughter board 216, a backplane 226 (FIG. 5), ceiling 206, and movable ceiling member 208.

Floor 210 and ceiling 206 each include a set of twenty slots 218. Floor 210 and ceiling 206 are made of a metal casting to provide structural support. Slots 218 are defined by plastic members that attach to the interior surface of the metal castings. Slots 218 are aligned such that each slot 218 on ceiling 206 is positioned directly above a corresponding slot 218 on floor 210, i.e., card cage 200 includes 20 slot pairs that are aligned in the vertical direction.

Daughter board 216 is sized to fit snugly between and within any two of the corresponding pairs of slots 218. As shown in FIG. 4, daughter board 216 is partially inserted into card cage 200. However, the length of daughter board 216 is approximately the same as the length of both floor 210 and ceiling 206. Thus, when fully inserted, the end of daughter board 216, which is visible in FIG. 4, lies flush with the end of card cage 200 at opening 214.

Ceiling 206 has a length that is shorter than the length of sidewalls 202, 204. The additional area created by the extra length of sidewalls 202, 204 is occupied by movable ceiling member 208, which is aligned with ceiling 206 in a horizontal plane. Movable ceiling member 208 also attaches to and extends between opposing sidewalls 202, 204. However, movable ceiling member 208 is not securely fixed.

Rather, movable ceiling member 208 is slidable in the direction of slots 218. Movable ceiling member 208 has two opposing edges that are directly adjacent to sidewalls 202, 204 and that each fit within a corresponding slide 222. Slides 222 are each formed by (1) an interior side of one of the sidewalls 202, 204 that provides lateral support, (2) an upper edge of structural support framework 220 that forms a lip along the edge of each sidewall 202, 204 to provide vertical support, and (3) a set of notches 244 extending in a horizontal line that is a uniform distance from the lip of support framework 220. Each notch 244 is a portion of one of sidewalls 202, 204 which is punched to form a notch. The line of notches 244 also provides vertical support.

Similarly, movable floor member 212 is attached to and extends between sidewalls 202, 204. Movable floor member 208 also is slidable in the direction of slots 218. Movable floor member 212 attaches along two slides 222 (only one slide being shown) that accommodate opposing side edges of movable floor member 212.

Similar to ceiling member 208 and floor member 212, movable ceiling member 208 and movable floor member 212 each include a set of twenty slots 218′. Slots 218′ are defined by plastic members that are identical to the members that define slots 218. Card cage 200 includes twenty slot pairs that are aligned in the vertical direction.

Card cage 200 is symmetrical about a plane that bisects card cage 200 into top and bottom portions. Card cage 200 also is symmetrical about a plane that bisects card cage 200 into left and right portions. Card cage 200 is assembled using parts having common structure. For example, sidewall 202, ceiling 206 and ceiling member 208 have the same structure as sidewall 204, floor 210 and floor member 212 respectively. Each of the corresponding parts are assembled in a position that is rotated 180 degrees from the position of the corresponding part, i.e., the corresponding parts face each other. Therefore, if card cage 200 were turned upside down, card cage 200 would have the same relative structure. Alternatively, card cage 200 could be manufactured without the above-described common parts, and card cage 200 could be asymmetrical either top to bottom or side to side. Thus, in essence, the corresponding parts of card cage 200 can be structurally the same and interchangeable or can be structurally distinct.

Card cage 200 is not symmetrical front to back. For example, as shown, movable ceiling member 208 is approximately ⅔ the length of ceiling member 208, and movable floor member 212 is approximately ⅔ the length of floor member 212. Alternatively, card cage 200 could be symmetrical from front to back.

As show in FIGS. 4 and 5, movable ceiling member 208 and movable floor member 212 are in unsecured positions. In the unsecured position, movable ceiling member 208 slides away from ceiling 206 and defines an opening 224 for receiving a printed circuit board, e.g., backplane 226 (FIG. 5). Movable floor member 212 slides away from floor member 212 and defines another opening 228, e.g., also for receiving backplane 226. As shown, both movable ceiling member 208 and movable floor member 212 can be completely removed from card cage 200 to provide one large contiguous opening. Alternatively, rather than being removable, the range of motion of both movable ceiling member 208 and movable floor member 212 could be limited within corresponding slides 222.

Backplane 226 is inserted transversely to slots 218 and slots 218′ and subsequently aligned. To align backplane 226 within card cage 200, four notches 410 (shown in, and discussed in greater detail in relation to, FIG. 11) of backplane 226 accommodate four corresponding registration pins 230 (only one registration pin being shown due to the perspective of FIG. 4). Each sidewall 202, 204 has two registration pins 230 that are symmetrically arranged as described above and that extend from the interior surface of sidewalls 202, 204. As backplane 226 is placed within card cage 200, registration pins 230 are disposed within corresponding notches 410 of backplane 226.

After backplane 226 is inserted and aligned, backplane 226 is attached within card cage 200. Sidewalls 202, 204 each include a corresponding support member 234 to attach the printed circuit board in position within card cage 200. Each support member 234 extends inward along the interior surface of corresponding sidewalls 202, 204. Support members 234 are punched from a section of corresponding sidewalls 202, 204 and are disposed at a 90 degree angle to corresponding sidewalls 202, 204. Each support member 234 has a support portion 236 that includes two holes 240. The holes accommodate screws that attach backplane 226 to card cage 200. Each support member 234 also has an attachment portion 238 that connects support members 234 to corresponding internal sides of sidewalls 202, 204. Alternatively, support members 234 could be, e.g., an L-shaped bracket riveted to the internal surface of corresponding sidewalls 202, 204.

After backplane 226 is inserted, aligned, and attached within card cage 200, movable ceiling member 208 and movable floor member 212 are placed in a secured position (FIG. 6) to firmly secure backplane 226 to card cage 200. Movable ceiling member 208 and movable floor member 212 each slide toward ceiling 206 and floor 210 respectively. Backplane 226 is sandwiched between ceiling 206 and movable ceiling member 208 as well as between floor 210 and movable floor member 212.

In the present embodiment, a variety of fastening mechanisms can be used to firmly secure backplane 226 between ceiling 206 and movable ceiling member 208 (or floor 210 and movable floor member 212). As shown most clearly in FIG. 4, movable ceiling member 208 and movable floor member 212 each include a set of fasteners 300 while ceiling 206 and floor 210 each include a set of studs 302. Studs 302 are aligned with corresponding fasteners 300 along an axis extending in the direction of slots 218, 218′. Both fasteners 300 and studs 302 include cooperative threads that allow card cage 200 to securely fasten backplane 226. An upper edge of backplane 226 fastens between ceiling 206 and movable ceiling member 208. A lower edge of backplane 226 fastens between floor 210 and movable floor member 212.

Card cage 200 also includes an additional securing mechanism to secure movable members 208, 212 in the secured position. The securing mechanism presses one of four corresponding corner portions of sidewalls 202, 204 between movable members 208, 212 and the head of one of four corresponding rotatable screws 246. A shank of each of the screws 246 extend into a corresponding corner of the movable members 208, 212. Each of the movable members 208, 212 have two screws 246 located on opposite side edges and nearest an exterior edge of movable members 208, 212.

The corresponding corners of sidewalls 202, 204 have a relieved portion that forms a slot 242. Each of the four slots 242 accommodates the shank of corresponding screws 246. When movable members 208, 212 are in the secured positions, the heads of the screws 246 can be rotated to secure movable members 208, 212. The securing mechanism additionally secures backplane 226. In addition, the securing mechanism provides a means to quickly secure movable members 208, 212 in the secured positions without engaging fasteners 300, e.g., when moving or installing card cage 200 within cabinet 100, e.g., prior to installing backplane 226.

As shown in FIG. 6, movable ceiling member 208 firmly secures backplane 226 when movable ceiling member 208 is in the secured position. Studs 302 of ceiling 206 extend through holes along the upper edge of backplane 226 while the lower edge of backplane 226 has notches that rest on studs 302 of floor 210. When each fastener 300 engages a corresponding stud 302 and is tightened, movable ceiling member 208 acts as a vice to firmly secure backplane 226 against ceiling member 208. Similarly, floor 210 and movable floor member 212 engage the lower edge of backplane 226. Thus, when movable members 208, 212 are in secured positions, backplane 226 is fixed in position.

Referring to FIGS. 7 and 8, fasteners 300 are captive metal fasteners that are permanently anchored in the casting of the corresponding movable floor member 212 (FIG. 4) or movable ceiling member 208 (FIG. 4). Fasteners 300 (as well as studs 302) are made of, e.g., 316 stainless steel. Each captive fastener 300 is arranged about a longitudinal axis 318. Each fastener 300 has a head 304, a shank 306 and a sleeve 308. Head 304 is attached to shank 306 and both rotate freely within sleeve 308.

Shank 306 includes a hollow interior portion 310 containing an internal thread 312. Hollow interior portion 310 faces, and is aligned with, stud 302 when fastener 300 is attached to movable members 208, 212. Thus, when movable members 208, 212 are in the secured positions, shank 306 fits over stud 302 and internal thread 312 cooperates with and engages an external thread 314 (FIG. 9) of stud 302.

Head 304 has, e.g., a hexagonal recess to accommodate an allen-type wrench. Thus, head 304 can be used to secure fastener 300 over stud 302. Head 304 interacts with sleeve 308 to partially captivate shank 306 within sleeve 308. Because head 304 is external to sleeve 308 and has an outer diameter that is wider than the internal diameter of sleeve 308, head 304 limits the movement of shank 306 in the direction of stud 302 along longitudinal axis 318.

A pair of internal ridges 320 and 322 complete the captivation of shank 306 within sleeve 308. Ridge 320 extends about the inner surface of sleeve 308 to form a circular ring. Ridge 322 extends about the outer surface of an end of shank 306 to form an opposing circular ring. Thus, as ridge 322 moves towards ridge 320, e.g., when fastener 300 is loosened, ridge 322 will ultimately engage ridge 320 and prevent further motion along longitudinal axis 318 in the direction away from stud 302.

Sleeve 308 further includes a ribbed portion 316 having a set of parallel ribs that extend completely about the circumference of the end portion. Ribbed portion 316 has ribs that extend longitudinally along fastener 300 and in the direction of slots 218 when fastener 300 is attached to one of movable members 208, 212.

To attach fastener 300 to one of movable members 208, 212, shank 306 is inserted into sleeve 308 prior to the complete formation of ridge 320. Ribbed portion 316 of sleeve 308 is clenched into a prefabricated hole in the metal casting of movable members 208, 212. Ribbed portion 316 provides both longitudinal resistance that tends to secure fastener 300 within the hole as well as rotational resistance that tends to prevent sleeve 308 from turning within the hole. Ribbed portion 316 reforms the metal casting around the ribs and may prevent cracking or other deformation of the casting, which may occur when a fastener having a serrated/toothed tip is clenched into a metal casting.

When fastener 300 is clenched into the metal casting, e.g., of movable ceiling member 208, an additional force is applied to head 304 which compresses sleeve 308 against the casting. Thus, ridge 320 is forced further inward and into a fully formed position that captivates shank 306.

Referring to FIGS. 9-10, each stud 302 has arms 324, 326 located on opposite ends of a support shank 328. Opposing arms 324, 326 extend in opposite directions from support shank 328 along longitudinal axis 318. Both of arms 324, 326 have external threads 314 sized to engage internal thread 312 of (FIG. 8) fastener 300.

Support shank 328 has two recesses 330 located on opposite sides of shank 328. Together, recesses 330 form a grip to accommodate a tool used to install stud 302 to either ceiling 206 or floor 210 (FIG. 4). Stud 302 is screwed into a prefabricated hole of one of the metal castings. Stud 302 can be screwed rather than clenched into the hole because a hollow passage is not required to pass shank 306 from one side of the hole to another. Stud 302 is symmetrical and either arm 324, 326 can be inserted into the prefabricated hole of the casting.

When installed, the entire external thread 314 can extend into and engage internal thread 312. However, the entire external thread 314 does not need to engage internal thread 312 to secure one of the movable members 208, 212 in the secured position. Thus, in combination, fastener 300 and stud 302 provide a range of positions in which movable members 208, 212 can be secured. In the present embodiment, movable member 208, 212 can be tight against backplane 226 within the range of positions provided by fastener 300 and stud 302. For example, each arm 324, 326 containing an external thread 314 is 0.375″ and can be entirely accommodated within fastener 300. In addition, fastener 300 can accommodate a portion of support shank 328. For example, stud 302 can extend into fastener 300 approximately 0.6″. Thus, in the secured position, card cage 200 can accommodate backplanes having various widths as long as the widths of the backplanes fall within the range of positions defined by stud 302 and fastener 300, e.g., between zero and less than 0.6″ (to provide sufficient engagement between threads 312, 314 to secure the backplane.)

The range of positions is limited by the threaded length of arms 324, 326 of stud 302 as well as by the internal length of internal thread 312 of fastener 300. Alternatively, therefore, a longer internal thread capable of accommodating a longer stud 302 would allow movable members 208, 212 to be secured through a wider range of positions.

Referring to FIGS. 11-12, backplane 226 includes a support device 400 to reinforce backplane 226 when daughter board 216 is inserted or extracted. Support device 400 is a stiffener to provide additional structural support. Support device 400 is metal finished with an electrodeposited zinc coating.

Support device 400 includes a cross member 402 which is a cross beam mounted horizontally and approximately bisecting backplane 226. Cross member 402 provides an opposing force in a direction of motion of the daughter boards along slots 218 to resist the force of daughter boards 216 against backplane 226. Cross member 402 is, e.g., 16.14″ in length, 0.375′ in width, and 0.438″ in depth. Cross member 402 includes three equidistantly spaced holes 412 through which cross member 402 can be attached to backplane 226 by screws. Cross member 402 also includes twenty equidistantly spaced guide holes 414 to provide a further mechanism to ensure backplane 226 is properly positioned.

Two end support members 404, 406 are attached to corresponding ends of the cross member, e.g., to form an H-shaped structure. End support members 404, 406 extend vertically along two side edges of backplane 226. Each end support member 404, 406 is, e.g., 6.75″ in length, 0.375″, in width and 0.438″ in depth. End support members 404, 406 provide a mechanism to secure cross member 402 and attach backplane 226 to sidewalls 202, 204 of card cage 200 (FIG. 4). For example, each end support member 404, 406 includes four holes 412′ to accommodate screws. The outer two holes 412′ of each end support member 404, 406 are used to attach each corresponding end support member 404, 406 to backplane 226. The inner two holes 412′ are used to attach the corresponding end support member 404, 406 to support member 234 of card cage 200 (FIG. 4). When backplane 226 is properly aligned, the two inner holes 412′ align with holes 240 of support member 234. When backplane 226 is not properly aligned, the two inner holes 412′ will be misaligned and the screws will not engage card cage 200 to secure backplane 226.

End support members 404, 406 can include additional structures. For example, the notch 410 provides a registration point as discussed above in conjunction with FIG. 4. Each support member 404, 406 includes two notches 410. Each notch 410 is a recess along an edge of one of end support members 404, 406. Notches 410 accommodate registration pin 430, which extends from and interior surface of sidewalls 202, 204. Each notch 410 is disposed on a corner of corresponding end support members 404, 406. Each notch 410 has an opening with a forward facing portion 410 a and a side facing portion 410 b (FIG. 12). Thus, as backplane 226 is positioned, backplane is moved forward and registration pin 230 enters notch 410 through the forward facing portion 410 a and, once in place, is disposed through side facing portion 410 b.

Each end support member 404, 406 also includes two guide holes 414′. Guide holes 414′ provide a further mechanism to ensure that backplane 226 is properly positioned.

End support members 404, 406 can be attached to cross member 402 using several different embodiments. For example, as shown in FIG. 13, end support members 404, 406 can be directly attached to the ends of cross member 402, e.g., by a weld, a rivet or a screw. In another embodiment, end support members 404, 406 can extend over the corresponding ends of cross member 402 but not be directly attached to the ends. In these embodiments, end support members 404, 406 can provide both a means to fix backplane 226 to card cage 200 as well as additional structural support for cross member 402. Alternatively, end support members 404, 406 can abut the corresponding ends of cross member 402 without overlapping the ends in the direction of motion of daughter board 216. In the later embodiment, end support members 404, 406 provide a means to attach backplane 226 to card cage 200 without further reinforcing cross member 402 in the direction of motion of daughter board 216. Also, support device 400 can be manufactured as a single integrated member.

Support device 400 is installed as part of backplane 226 prior to installing backplane 226 within card cage 200. Thus installed, backplane 226 has additional structural support, a mechanism to register the position of backplane 226 within card cage 200, a mechanism to quickly attach backplane 226 to card cage 200, and cabinet 10 has a reduced part count at the time of installing components such as backplane 226.

Support device 400 is symmetrical about a horizontal axis, i.e., an axis extending longitudinally along cross member 402. Support device is also symmetrical about a vertical axis, i.e., an axis parallel to end support members 404, 406. The structure of both end support members 404, 406 is identical. Therefore, end support members 404, 406 are interchangeable. Also, cross member 402 can be installed as shown or rotated 180 degrees with each end of cross member 402 adjacent to the opposite end support member 404, 406.

In addition, support device 400 can be installed on either side of backplane 226. Thus, as shown in FIG. 12, an identical supplemental support member 400′ can be installed upon the opposite side of backplane 226. As shown, supplemental support member 400′ entirely overlays support member 400 in the direction of motion of daughter board 216. Thus, supplemental support member 400′ is expected to provide improved reinforcement and support of backplane 226.

Referring to FIGS. 15-16, daughter board 216 includes a different type of stiffener 500 for inserting and removing daughter board 216, e.g., from slot 218 (FIG. 4) without buckling or breaking daughter board 216. Stiffener 500 is a rigid elongated member that has an elongated channel 502 that extends along the elongated member. Stiffener 500 includes an engagement portion 510, a driver portion 512 and a force translator portion 520 extending between engagement portion 510 and driver portion 512. Stiffener 500 is, e.g., metal finished with an electrodeposited zinc coating.

Channel 502 is defined by three distinct portions of stiffener 500: two lateral portions 504, 506 extend in parallel from a cap portion 508. The three portions 504, 506, 508 are connected at right angles to form a U-shaped member. Stiffener 500 attaches to daughter board 216 along an edge of daughter board 216 that moves through slot 218. The edge of daughter board 216 fits within channel 502, and stiffener 500 extends substantially along the entire edge of daughter board 216, e.g., from a front portion of daughter board 216 where force is applied to a back portion of daughter board 216 where force is distributed.

When attached to daughter board 216, stiffener 500 is oriented so that engagement portion 510 receives a force applied either to electrically connect daughter board 216 with backplane 226 (FIG. 5) or to electrically disconnect daughter board 216 from backplane 226.

Engagement portion 510 flares downward away from cap portion 508 to provide additional area in which to place a hole 514 to accommodate a pivot pin 516. Pivot pin 516 provides both an attachment mechanism as well as a fulcrum to apply insertion and extraction forces. As shown most clearly by comparing FIGS. 15 and 16, when stiffener 500 is attached to daughter board 216, pivot pin 516 extends through both engagement portion 510 and a card injector/ejector lever 518. Thus, due to the force of pivot pin 516 against engagement portion 510, force applied from lever 518 is translated through stiffener 500.

Alternatively, engagement portion 510 can be oriented in other position. For example, the end of engagement portion 510 could abut pivot pin 516 to translate an insertion force without directly contacting pivot pin 516 when an extraction force is applied to daughter board 216. Similarly, stiffener 500 could be attached to daughter board 216 without abutting pivot pin 516 when either an extraction or insertion force is applied to daughter board 216.

When attached to daughter board 216, stiffener 500 is oriented so that driver portion 512 is directly adjacent to a surface of electrical connector mechanism 522. Electrical connector mechanism includes the electrical connectors that engage backplane 226. Driver portion 512 forms a right angled notch that abuts a corner surface of electrical connector mechanism 522 to force electrical connector mechanism 522 into electrical connectors of backplane 226 and electrically connect daughter board 216 to backplane 226.

As configured, driver portion 512 does not exert a force on electrical connector mechanism 522 during extraction of daughter board 216 because driver portion 512 abuts electrical connector mechanism 522 and is not otherwise attached to connector mechanism 522 in the opposite direction. Rather, during extraction of daughter board 216, the extraction force is translated through stiffener 500 and applied to daughter board 216 via attachment points 514′, 514″.

Attachment points 514′, 514″ are parallel pairs of tabs arranged along stiffener 500 on opposite sides of channel 502. Each tab of attachment points 514′, 514″ includes a hole to accommodate a screw or a pin. The pairs of holes of each attachment point 514′, 514″ are aligned across channel 502 so that, e.g., the screw or pin extends through the holes and through the daughter board 216.

During insertion of daughter board 216, attachment points 514′, 514″ are thought to distribute the applied force through daughter board 216 in conjunction with driver portion 512. During extraction, attachment points 514′, 514″ are thought to bear the entire force applied force through engagement portion 510 (discounting frictional forces between stiffener 500 and daughter board 216). However, alternatively, driver portion 512 could include, e.g., an additional lip or ridge capable of engaging connector mechanism 522 during extraction of daughter board 216. In such a configuration, driver portion 512 would distribute some or all of the force applied to engagement portion 510.

One skilled in the art may now make numerous modifications and uses of and departures from the specific apparatus and techniques disclosed herein without departing from the inventive concepts. The invention has been described with reference to vertical and horizontal directions. However, other orientations are possible (e.g., card cage 200 could be rotated 90 degrees to lie on one side). All materials, dimensions, configurations, orientations, and combinations are provided as illustrative examples only and are not intended to be the only possible embodiments within the scope of the claims. Consequently, the invention is to be construed as embracing each and every novel feature and novel combination of features present in or possessed by the apparatus and techniques disclosed herein and limited only by the spirit and scope of the appended claims. 

What is claimed is:
 1. A printed circuit board card cage comprising: a first pair of opposing sidewalls, such sidewalls in the first pair thereof being disposed in first and second laterally spaced parallel planes, respectively, to provide a first space between the first pair of opposing sidewalls a second pair of opposing sidewalls, such sidewalls in the second pair thereof being disposed in the first and second laterally spaced parallel planes, respectively, to provide a second space between the second pair of opposing sidewalls; the first pair and second pairs of sidewalls being slideable relative to each other along a direction parallel to the first and second planes to provide a backplane printed circuit board receiving region between the first pair of opposing sidewalls and the second pair of opposing sidewalls when such first and second pair are slid apart into an open position to enable such receiving region to receive a backplane printed circuit board disposed transversely to the first and second planes and to have edges of the first pair of sidewalls engage portions of the backplane printed circuit board and have edges of the second pair of sidewalls engage opposite portions of the backplane printed circuit board when the first and second pair of sidewalls are slid towards each other to close the received backplane printed circuit within the printed circuit board receiving region; the first pair of sidewalls having slots therein to receive edge portions of a set of daughter boards and such first region being configured to receive therein the set of daughter boards and enable such set of daughter boards to be plugged into one side of the backplane a fastening device adapted to urge the second member to slide toward the first member to clamp the printed circuit board in the opening between the first and second sidewalls when the first and second sidewalls are in contact with the printed circuit board to provide the secured position by fixing the backplane within the backplane printed circuit board receiving region, such fastening device comprising: a stud attached to one of the sidewalls of the first pair of sidewalls and extending toward an opposing one of the sidewalls in the second pair of sidewalls, the stud having a threaded portion; and a captive fastener attached to the opposing one of the sidewalls of the second pair of sidewalls, the fastener having a cooperative thread; and wherein the fastener is aligned with the stud, the cooperative thread of the fastener being capable of engaging the threaded portion of the stud, the device being capable of clamping the backplane printed circuit board between the opposing first and second pair of sidewalls when the fastener engages the stud.
 2. The cage recited in claim 1 wherein the second pair of sidewalls have slots therein to receive edge portions of a second set of daughter boards and such second region being configured to receive therein the second set of daughter boards and enable such second set of daughter boards to be plugged into an opposite side of the backplane printed circuit board.
 3. The cage of claim 2 wherein the fastener is aligned with the stud along an axis and the fastener is movable relative to the stud along the axis.
 4. The cage of claim 1 wherein the fastener further comprises: a hollow cylindrical sleeve disposed about an axis, the sleeve having a surface portion for attaching the fastener to said opposing one of the sidewalls of the second pair of sidewalls, the sleeve having an internal captivating surface; a shank extending through the sleeve, the shank including the cooperative thread along a first and adjacent to the stud, the shank being rotatable within the sleeve, the shank having an external captivating surface capable of engaging the internal captivating surface to limit motion of the shank along the axis such that at least some portion of the shank remains within the sleeve.
 5. The cage of claim 4 wherein the shank further comprises a head attached to an end of the shank.
 6. The cage of claim 5 wherein the head is external to the sleeve.
 7. The cage of claim 6 wherein a width of the head is greater than an interior width of the sleeve such that the head is capable of engaging the sleeve to limit motion of the shank along the axis toward the stud.
 8. The cage of claim 6 wherein a surface of the head forms a portion of the external captivating surface.
 9. The cage of claim 6 wherein the head includes a rotating means for applying a rotational force to the shank.
 10. The cage of claim 4 wherein the surface portion for attaching the fastener to the opposing one of the sidewalls of the second pair of sidewalls comprises a plurality of parallel ribs extending in the direction of the axis, the ribs adapted to engage the opposing one of the sidewalls of the second pair of sidewalls and oppose rotation of the sleeve relative to the opposing one of the sidewalls of the second pair of sidewalls.
 11. The cage of claim 1 wherein the stud further comprises: opposing arms and a support shank, the opposing arms extending in opposite directions from the support shank along an axis, one arm including the threaded portion, the opposing arm including a second threaded portion for attaching the stud to said one of the sidewalls of the first pair of sidewalls.
 12. The cage of claim 11 wherein the support shank comprises: a grip adapted to engage a tool for rotating the stud relative to said one of the sidewalls of the first pair of sidewalls.
 13. The cage of claim 12 wherein the grip includes two recessed portions disposed along opposing sides of the support shank. 